Spirit as seen from HiRISE
HiRISE has spotted all of the successful Mars landers and rovers,
and is now being used to search for the unsuccessful ones, particularly
Mars Polar Lander. Source Credit:
NASA / JPL / U. Arizona
The sharp-eyed HiRISE camera has been able to spot landers, parachutes,
and other hardware from all the successful NASA landers on Mars: both Viking
Landers, Mars Pathfinder, and both the Spirit and Opportunity landing sites. However,
the many missing Mars landers, including Mars 2, Mars 3, Mars 6, Beagle
2, and Mars Polar Lander, have not yet been found. The successful
landers could be spotted in HiRISE image because they returned panoramic
photos that allowed mappers to determine their approximate locations on
lower-resolution images from earlier spacecraft, so the high-resolution
HiRISE images could be targeted precisely at the actual landing sites.
But for the missing landers, the landing sites can only be guessed at based
on tracking data and the last known positions of the spacecraft as they approached
Mars for their landings. The large uncertainty in the locations of the
missing landers means that many HiRISE images are required to cover the possible
landing region; for the Russian landers, "many" means an impractically
large number, hundreds or even thousands. The missing lander that has
the best possibility of being found is Mars Polar Lander. Its crash site
is fairly well constrained, likely to be within an ellipse about 25 by 50 kilometers
in extent.
Even if HiRISE captures an image that does cover a crash site, there is no
guarantee that the spacecraft can be identified on the image. Actually,
the spacecraft themselves are not the best objects to search for, because they
are relatively small. Based on the images of successful landers, the easiest
hardware to spot from orbit is a lander's protective backshell and parachute. Of
the missing landers, all but one (Mars 2) is thought to have deployed its parachute
before crashing. A parachute is a large, bright object and so should,
theoretically, be possible to spot in HiRISE images over crash areas.
Here is what the backshells and parachutes of all the successful landers have
looked like to HiRISE.
Backshells and parachutes on Mars as seen by HiRISE
Mars Reconnaissance Orbiter has successfully imaged all six of the successful Mars landers: Phoenix, Spirit, Opportunity, Mars Pathfinder, and the Viking 1 and 2 landers. For most of these, it was easier to spot the backshells and attached parachutes than the actual landers. Provided they are not obscured by dust, the white parachutes appear bright against the Martian ground, and are much larger than the landers.
Credit: NASA / JPL / U. Arizona / montage by Emily Lakdawalla
The parachutes are easy to spot in the Pathfinder
and Mars Exploration Rover landings from 1996 and 2004. The Viking parachutes
are more difficult. Viking 1's is visible as a smudge, probably covered
with dust, to the south of the backshell. There is no obvious candidate
for Viking 2's parachute. Mars Polar Lander disappeared in 1999, so
there is hope that its parachute should be at least as bright as Pathfinder's. However,
the polar location might have resulted in modification of the appearance crash
site due to it being covered with seasonal carbon dioxide frost during the
four Martian winters between 1996 and 2008.
For comparison, here is what the landers have looked like to HiRISE.
Six successful landers on Mars as seen by HiRISE
Mars Reconnaissance Orbiter has successfully imaged all six of the successful Mars landers: Phoenix, Spirit, Opportunity, Mars Pathfinder, and the Viking 1 and 2 landers. Since the landers are only approximately two meters in diameter, they are only a few pixels across even at the extreme resolution of the HiRISE camera.
Credit: NASA / JPL / U. Arizona / montage by Emily Lakdawalla
HiRISE Images over the Mars Polar Lander Landing Site
These are the images captured to date over the Mars Polar Lander landing
ellipse. They
are concentrated primarily on the western half of the ellipse because a small
change in the definition for longitudes on Mars was made between the time that
the Mars Polar Lander trajectory was reconstructed and the time that the HiRISE
imaging campaign began. Since it is winter at the south pole through
the rest of 2008, there will be no new images added to this list until the
Sun returns in 2009. A Google Mars map of the image locations can be found
here.
The HiRISE search for Mars Polar Lander
Mars Polar Lander disappeared as it approached Mars for its landing in 1999. It was originally targeted at the site marked with the blue diamond on this map. As part of the investigation into its disappearance, the entry, descent, and landing team modeled what they knew of the spacecraft and Martian atmosphere conditions on the date that Mars Polar Lander approached. Those models, made after the landing attempt, produced the landing ellipses shown here. The dark blue ellipse is the 2-sigma landing ellipse; the dashed line is the associated scatter ellipse. The square is the center of the landing ellipse, where Mars Polar Lander is considered most likely to have fallen. Mars Reconnaissance Orbiter arrived at Mars in 2006 and began a campaign to cover the landing ellipse with images from the HiRISE camera. The map shows the HiRISE images taken as of May 2008; they cover primarily the western half of the ellipse.
Credit: NASA / JPL / Tim Parker
How to Search
If you would like to volunteer to carefully search one or more images as part
of the concerted search effort, . Indicate
if you have a preference which image you would like to search.
The easiest way to search the HiRISE images is to take advantage of the IAS
Viewer, a Java application that you can download from the HiRISE website. This
software does not require you to download the complete image (which may be
1 GB or more of data) before you start browsing it. Follow the links
under the "JP2 Quicklook (IAS Viewer)" button on the right side of
each image page. For users who cannot download and install software (schoolteachers,
this probably means you), you can make use of a different tool, called "Zoomify."
If you think you have found a candidate piece of lander hardware, send an
email to with the filename of the image (for example,
PSP_005958_1025_RED.NOMAP.JP2) and the pixel coordinates of the candidate (which
you may read from the "Location" window in the IAS Viewer software). Please
include a brief description of the candidate feature.
Some Key Facts to Consider If You Want to Search
Read the image "metadata" carefully before you begin to search. In
particular, pay close attention to the direction from which the image is
illuminated. The "azimuth" to north or to the Sun is given
in degrees, measured clockwise from the right side of the image. So,
for an image with a sub-solar azimuth of 50 degrees, the Sun is illuminating
the image from the lower right. Many of these images have the solar
illumination coming from the bottom, a configuration that tends to make topography
appear inverted, with bumps appearing as holes and vice versa.
You must search the full-resolution HiRISE images, and search
them at very nearly the highest zoom level (zoom in to at least 25% of the
full resolution) in order to have a hope of spotting the lander hardware. The
hardware will be invisibly small in the "browse" HiRISE images
listed under "JPEG products" on the right side of the image page. Use
the "JP2 Quicklook (IAS viewer)" links on the HiRISE website
to search the full-resolution data.
If you find something you consider to be a candidate, figure out its scale
to make sure it makes sense. A parachute won't be more than about 8
meters long, or 32 pixels at the highest resolution of 25 centimeters per
pixel. The backshell is roughly 3 meters (12 pixels) in diameter. The
lander will be smaller. Any fragments of a crashed spacecraft will
be even smaller. "Candidates" that are larger than
this cannot be the missing hardware.
Beware of cosmic ray hits (see image below). They most often look
like narrow, bright streaks, but they sometimes have a curved shape, and
can easily be mistaken for lander hardware or for crashed spacecraft pieces.
If a candidate is in the center two columns of a HiRISE image strip, there
may be color data. Human-built hardware is generally more blue than
red Mars.
The IAS Viewer sometimes stretches the contrast of the images in such a
way that parts of the image become washed out. To adjust the
contrast of an image, fiddle with the histogram settings in the IAS Viewer.
Cosmic ray hits in HiRISE images
When cosmic rays hit the CCD detector of HiRISE (or any other camera), they can leave a bright streak. Such streaks could easily be mistaken for parts of missing lander hardware, so caution should be taken in the interpretation of bright spots in HiRISE pictures.
Credit: NASA / JPL / U. Arizona / Tim Parker / Rob Manning
[ what is this? ]